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. Author manuscript; available in PMC: 2011 Feb 19.
Published in final edited form as: J Org Chem. 2010 Feb 19;75(4):1101. doi: 10.1021/jo9022099

Table 2.

L-Proline-Catalyzed Aldol Reaction of Racemic α-Ketophosphinates and Acetonea

graphic file with name nihms171603u3.jpg
entry R T (°C) time (h) yield (%)b ee (%)c drd
7 8
1 Ph(a) -30 96 58 99 91 52:48
2 4-F-C6H4(b) -30 120 67 98 91 50:50
3 3-FC6H4(c) 0 36 89 96 80 52:48
4 4-BrC6H4(d) -30 120 70 97 87 54:46
5 4-ClC6H4(e) -30 120 65 94 73 52:48
6 3-ClC6H4(f) 0 36 92 99 89 53:47
7 4-MeC6H4(g) -30 120 45 90 80 54:46
8 4-MeOC6H4(h) rt 40 87 93 71 56:44
9 graphic file with name nihms171603t1.jpg rt 48 85 84 62 46:54
10 Me(j) rt 24 88 95 87 44:56
11 Et(k) rt 40 90 87 61 45:55
a

Unless otherwise indicated, all reactions were carried out with the racemic ketophosphinate (0.50 mmol) in dry acetone (2.0 mL), with L-proline (0.10 mmol, 20 mol %) as the catalyst for the specified reaction time and temperature.

b

Total yield of the inseparable diastereomers (7 and 8) isolated after column chromatography.

c

Enantioselectivity was determined by HPLC analyses, due to the overlap some of the peaks, the error limits maybe is considerably larger than normal in those cases.

d

The ratio of 7:8 or vice versa; determined by 1H NMR analyses.